13,496 research outputs found
Improved lattice QCD with quarks: the 2 dimensional case
QCD in two dimensions is investigated using the improved fermionic lattice
Hamiltonian proposed by Luo, Chen, Xu, and Jiang. We show that the improved
theory leads to a significant reduction of the finite lattice spacing errors.
The quark condensate and the mass of lightest quark and anti-quark bound state
in the strong coupling phase (different from t'Hooft phase) are computed. We
find agreement between our results and the analytical ones in the continuum.Comment: LaTeX file (including text + 10 figures
Spectroscopy and large scale wave functions
We discuss the relevance of long wavelength excitations for the low energy spectrum of QCD, and try to develop an efficient method for solving the Schrodinger equation, and for extracting the glueball masses and long wavelength functions of the ground and excited states. Some technical problems appearing in the calculations of SU(3) gauge theory are discussed
Hamiltonian lattice QCD at finite chemical potential
At sufficiently high temperature and density, quantum chromodynamics (QCD) is
expected to undergo a phase transition from the confined phase to the
quark-gluon plasma phase. In the Lagrangian lattice formulation the Monte Carlo
method works well for QCD at finite temperature, however, it breaks down at
finite chemical potential. We develop a Hamiltonian approach to lattice QCD at
finite chemical potential and solve it in the case of free quarks and in the
strong coupling limit. At zero temperature, we calculate the vacuum energy,
chiral condensate, quark number density and its susceptibility, as well as mass
of the pseudoscalar, vector mesons and nucleon. We find that the chiral phase
transition is of first order, and the critical chemical potential is (dynamical quark mass at ). This is consistent with
(where is the nucleon mass at ).Comment: Final version appeared in Phys. Rev.
Transport properties and magnetic field induced localization in the misfit cobaltite [BiBaKCo][CoO] single crystal
Resistivity under magnetic field, thermopower and Hall coefficient are
systematically studied for
[BiBaKCo][CoO] single crystal.
In-plane resistivity ((T)) shows metallic behavior down to 2 K with
a dependence below 30 K; while out-of-plane resistivity ()
shows metallic behavior at high temperature and a thermal activation
semiconducting behavior below about 12 K. Striking feature is that magnetic
field induces a ln(1/) diverging behavior in both and
at low temperature. The positive magnetoresistance (MR) could be
well fitted by the formula based on multi-band electronic structure. The
ln(1/) diverging behavior in and could arise from
the magnetic-field-induced 2D weak localization or spin density wave.Comment: 7 pages, 8 figure
Evaluation of a rapid test for detection of H5N1 avian influenza virus
The performance of H5 Dot ELISA, a rapid test for detection of avian H5N1 influenza virus, was evaluated using 30 H5N1 strains belonging to 10 major genetic groups of H5N1 influenza virus, 14 strains of non-H5N1 influenza virus and 652 field samples collected from healthy and diseased chickens from markets and poultry farms. The detection limit of the test for all 30 strains of H5N1 virus was ≤0.1 hemagglutinin (HA) units and the test yielded a negative result when tested against 100 HA units of the non-H5N1 viruses. The test gave a positive result for 87 of the 106 poultry samples from which H5N1 virus was isolated by culture and 3 of 546 culture-negative poultry samples. Compared with virus culture, the overall prediction rate of the test was determined to be 96.6%; the positive prediction rate was 96.7% and negative prediction rate, 96.6%. The false positive rate was 0.5% and false negative rate 17.9%. Considering that the test is also convenient to use, it was concluded that H5 Dot ELISA is suitable for field use in the investigation of H5N1 influenza outbreaks and surveillance in poultry. Crown Copyright © 2008.postprin
The Coupled Cluster Method in Hamiltonian Lattice Field Theory: SU(2) Glueballs
The glueball spectrum within the Hamiltonian formulation of lattice gauge
theory (without fermions) is calculated for the gauge group SU(2) and for two
spatial dimensions.
The Hilbert space of gauge-invariant functions of the gauge field is
generated by its parallel-transporters on closed paths along the links of the
spatial lattice. The coupled cluster method is used to determine the spectrum
of the Kogut-Susskind Hamiltonian in a truncated basis. The quality of the
description is studied by computing results from various truncations, lattice
regularisations and with an improved Hamiltonian.
We find consistency for the mass ratio predictions within a scaling region
where we obtain good agreement with standard lattice Monte Carlo results.Comment: 13 pages, 7 figure
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